Tallis in Wonderland

Where Is My Itch?

Raymond Tallis is itching to find out.

I am lying in darkness, trying to sleep. There is a tiny whining sound. It stops. I brace myself: the mosquito has landed. Shortly afterwards – a sting. In the confusion, the beast escapes my wildly swatting hands, and I am left alone with my itch. Vengeance denied me, and the possibility of sleep made even more remote, I philosophise.

Where is that itch? Well, it’s on my leg of course, where the little bastard landed, took out its hypodermic, and injected histamine, prior to siphoning off a minute aliquot of my life-blood. Of this there can be no doubt because this is where, later, I see a little papule, and where I have to scratch in search of relief. It’s certainly not on my arm, in my liver, on the bed, or in the next room. If I go to the bathroom in search of ointment, my itch goes with me.

Regular readers of Philosophy Now will already be uneasy. An itch is a content of consciousness, and such phenomena, we are often told, aren’t the kinds of things that can have locations in space, even bodily space. In the case of thoughts, memories and mental images, it is easier to say why it’s odd to assign them to a point in space: they have aboutness or reference – they point beyond themselves, and so they cannot be in what or where they are about.

Let’s stick with thoughts for the moment. Suppose I think, “The Battle of Hastings took place in 1066.” The thought has two analytical aspects: it is a token that occurs at a particular time (say at 3 a.m., just after I have been bitten by a mosquito); and it is also an instance of a type, that is, an expression of a proposition. I alone have the token, the individual instance; but many people can entertain the same proposition about the Battle of Hastings. Indeed, I can have the token only because others have had the type it instantiates: it has, as it were been ‘handed down’ to the present from 1066, when the events corresponding to the content of my thought were observations made by participants and eye witnesses. In short, the token is a psychological phenomenon, and the type is something else: it is the content or reference of the thought, which presents itself as a fact, or a possible fact. And a particular thought’s status as an instance of a type makes it something to which it does not seem right to ascribe a spatial location.

Where Is My Thought?

In the most famous moment in Western philosophy, René Descartes came to the conclusion that he was identical with his thoughts because these were the only items whose existence he could not doubt, since the very process of doubting that his thoughts were real would itself be a process of thought. What is more, he concluded, if he were thinking, he could not doubt his own existence, since if he didn’t exist, he couldn’t think. Hence his famous formula cogito ergo sum: ‘I think, therefore I am’. (It has never been very clear how much his argument actually delivered safely from the jaws of doubt. For a pitilessly detailed discussion, see my I Am: A Philosophical Inquiry into First-Person Being, Edinburgh University Press, 2004.) What is relevant for our present purposes is that Descartes believed that his thoughts were parts of a ‘thinking substance’, and that this substance, unlike the material substance of his body, was not spatially extended, or, indeed, spatially located. Avowedly anti-Cartesian twentieth century analytical philosophers would agree with him in this respect: influenced by the German philosopher Gottlob Frege, they believed that the essence of thought was the thought type – the proposition expressed in the thought – not the thought token – not the psychological event hosted by individual bearers of thoughts like me, and occurring (say) at 3 a.m., just after I have been bitten by a mosquito.

More recently, however, some philosophers have focussed on token thoughts, and have argued that these items occur not only at a particular time, but at a particular place: they are located in the brain of the person thinking them. A thought is where a brain scan lights up when someone is having it. When we are sufficiently adept at brain-reading, we shall then become thought-readers. So thoughts are thus re-inserted into space, along with the mind of the thinker, even though there remain aspects of thoughts – their meaning or reference – which (to use Hilary Putnam’s phase) “ain’t in the head.”

Itches, of course, are not like thoughts. Indeed, Descartes was rather sniffy about such bodily feelings: they were ‘confused thoughts’ incurably curdled by the body from which they were inseparable. At any rate, they lack thought’s double aspect of being a token psychological event and a proposition that the event refers to or instantiates. Itches are not about anything. Any temptation to think that my itch is about its cause, the mosquito, or its bite, may be resisted by recalling I can have an itch without having any idea of its cause – without its being ‘an itch about’ a mosquito bite, or even about the idea of the bite.

Itches lack the aboutness that prevents other thoughts from being in any particular place; so is it OK to locate itches? If so, where? According to the now standard view, the itch is not in my leg, where the bite can be seen, and where scratching brings relief. The itch is in my sensory cortex. Other parts of the brain may be involved – as when I think bitterly of the little bastard that bit me – but it is the sensory cortex that is most crucially involved. There is a connection from the sense-endings in the skin which were stimulated by the bite, up the spino-thalamic tracts, thence through the thalamus, to the sensory cortex at the surface of the brain. It is there, we are told, that the itch is experienced, that is to say, comes into being. If the nerves between the sense-ending and the cortex are cut, or if the relevant bit of the cortex is damaged, no itch is felt. So itches aren’t really in the leg, but in the brain.

Tallis Through The Looking Glass

The careful reader (every reader of this column) will have spotted a bit of fancy footwork here. The argument that, since the itch is not felt unless there is activity in the relevant bit of the brain, it follows that the itch is in that bit of the brain, looks fishy. If you asked me where my itch was, I would point to my leg where I was bitten and not to my head. The bite and the itch are, surely, in the same place.

We have not, however, reached QED yet. Those who maintain that the itch is really in the brain, not the leg, concede that it seems to be in my leg. But, they say, it seems to be there only because it is located in that part of my body image or ‘schema’ which I take to be my leg – yet the body schema is a construct of the brain. According to John Searle, “the match between where the sensation seems to be and the actual physical body is entirely created in the brain” (The Mystery of Consciousness, 1998, p.182). The proof of this, he says, comes from phantom limb sensations. I can experience pain in a limb that has been amputated. This is because I still have a two-legged body schema in my brain, to which brain events, such as activity in pain pathways, can be referred.

Not so fast. We experience pains in limbs we no longer have only because we usually experience pains in limbs we do have. Phantom limb sensations are referred to non-existent legs only because of ordinary sensations that are felt in real legs, prompted by real events. I feel an itch in my leg when I am bitten there; and I point to my leg when asked where the itch is because here is where I need to scratch or dab the soothing ointment. Yes, I could deactivate a bit of my brain and the itch would go, but it is perverse to conclude that this – admittedly one of the necessary conditions of the itch – is where the itch is.

Besides, the claim that the itch is really located inside an image of the body created in the brain would have rather extraordinary consequences. Let me illustrate this with something that has bothered me since 1961. Between puffs on his Woodbine, Ned Ellis, my physics teacher, once asked the class where mirror images were. We gave the standard answer: they are as far behind the mirror as the object reflected was in front of it. No, he said: they are in your brain. And he reminded us that if you looked behind the mirror, you wouldn’t see the image. It is we who construct the image and locate it out there in the world. But this cannot be extended to objects as well as images. We do not locate the mirror in the world: it is located there without our help, thank you. However, whole hog neurological idealism holds that not only the mirror image, but also the mirror (purchased at the local DIY shop), and all the objects reflected in it, are in some sense constructs of our brains. This idea is widely accepted. The distinguished neuroscientist Chris Frith expresses it succinctly in Making up the Mind: How the Brain Creates Our Mental World (2007): the brain “makes up the mind” which in turn models, or houses the model of the world. If this were true, the brain itself (and brain science, and the equipment it uses) would be a somewhat problematic construct somehow collaborating with a community of constructs to discover that, like everything else we’re aware of, it is a construct.

Itches of course should be easier to think about than thoughts or mirror images. Unlike thoughts, they are not two-faced – they’re not psychological tokens instantiating general propositions. And they are not constructs like mirror images, although the latter (pace Ned Ellis) fit uneasily into the head because they are available to and confirmed by others: I can ask others to look at a mirror image which we can both see. Itches are not shared like thoughts or mirror images: others can infer my itch from the bite on my skin or my scratching, but they cannot experience it. Even so, itches are problematic. The answer to the question of ‘where’ the itch is – in my leg, in my brain, in a mental model constructed by my brain, or as an inhabitant of a Cartesian thinking substance – will depend on what kind of space, and what kind of ‘in’, we are thinking of. The space of sensations such as itches will be different from the dual space of thought, where the space of psychology is married to the space of logic and semantics – of meaning and reference. And it will be different again from the space inhabited by mirror images. At any rate, the idea that the itch is ‘really’ in my brain but is ‘referred to’ my leg (by what means, and by whom, is unclear) does not capture the sense that my itch really is in my leg. For the present, I will stubbornly insist that if it makes sense to locate a sensation, it is where I feel it, not in my brain or in some model of my body created in the brain.

In Plato’s Apology, Socrates described himself as a ‘gad-fly’, “arousing, persuading and provoking.” My mosquito has provided the same service, causing much head-scratching as well as leg-scratching. But I want to sleep, and I can hear the little pest returning. Time to reach for the hemlock aerosol.

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